The present invention relates generally to inlet structures for hypersonic vehicles, and more particularly to a system and method for controlling the inlet shock position of a hypersonic vehicle using controlled temperature fuel injection into the inlet.
Hypersonic vehicles typically lack aircraft-like performance and maneuverability at speeds greater than Mach-5. Accordingly, conventional structures for hypersonic vehicle generally include a variable geometry intake structures for the propulsion system. These structures use moving walls for the inlet operated by mechanical actuators that require some form of power, typically from a hydraulic system of pumps, pipes and actuators. There is thus a structural weight and complexity penalty and power requirements for the actuation subsystem having no other use aboard the vehicle.
The invention solves or substantially reduces in critical importance problems with prior art inlet structures for hypersonic vehicles as just described by providing system and method for injecting thermally controlled fuel into the airflow at the inlet of the propulsion system for the vehicle. The Mach number of the airflow entering the inlet and the shock angle of the flow at the inlet is thereby controllable. The inlet may therefore be structured to a fixed geometry for the lowest convenient Mach number and the airflow into the inlet is controllable to higher operating Mach numbers using fuel injection according to the invention. Combustion efficiency within the engine of the vehicle is not negatively affected by controllably positioning the shock angle of the flow into the inlet. The structure defining the invention is substantially only an extension of the structural cooling system that will be required in any high-speed flight vehicle. Further, the fuel injected into the inlet airflow would comprise a fuel/air mixture at elevated temperatures that would contribute positively to the thermodynamic effects on the inlet flow. The fuel/air mixture that is introduced into the inlet airflow is mixed at least as well as the combustor fuel and therefore contributes positively to efficient operation of the engine.
It is a principal object of the invention to provide structure and method for controlling the shock position and airflow Mach number at the inlet of a hypersonic vehicle.
It is another object of the invention to provide structure and method for controlling the inlet shock position and airflow Mach number of a hypersonic vehicle using hot fuel injection.
These and other objects of the invention will become apparent as a detailed description of representative embodiments proceeds.